The present invention relates to the field of mass-storage devices. More particularly, this invention relates to a smart tester and method for testing a bus connector, for example a SCSI connector for a SCSI disc drive.
Devices that store data are key components of any computer system. Computer systems have many different types of devices where data can be stored. One common device for storing massive amounts of computer data is a disc drive. The basic parts of a disc drive are a disc assembly having at least one disc that is rotated, an actuator that moves a transducer to various locations over the rotating disc, circuitry that is used to write and/or read data to and from the disc via the transducer, and a bus interface to connect the disc drive into an information-handling system. The disc drive also includes circuitry for encoding data so that it can be successfully retrieved from and written to the disc surface. A microprocessor controls most of the operations of the disc drive, in addition to passing the data back to the requesting computer and receiving data from a requesting computer for storing to the disc.
The disc drive includes a transducer head for writing data onto circular or spiral tracks in a magnetic layer the disc surfaces and for reading the data from the magnetic layer.
The transducer is typically placed on a small ceramic block, also referred to as a slider, that is aerodynamically designed so that it flies over the disc. The slider is passed over the disc in a transducing relationship with the disc. Most sliders have an air-bearing surface (xe2x80x9cABSxe2x80x9d) which includes rails and a cavity between the rails. When the disc rotates, air is dragged between the rails and the disc surface causing pressure, which forces the head away from the disc. At the same time, the air rushing past the cavity or depression in the air bearing surface produces a negative pressure area. The negative pressure or suction counteracts the pressure produced at the rails. The slider is also attached to a load spring that produces a force on the slider directed toward the disc surface. The various forces equilibrate so that the slider flies over the surface of the disc at a particular desired fly height. The air lubrication film eliminates the friction and resulting wear that would occur if the transducing head and disc were in mechanical contact during disc rotation. In some disc drives, the slider passes through a layer of lubricant rather than flying over the surface of the disc.
Information representative of data is stored on the surface of the storage disc. Disc-drive systems read and write information stored on tracks on storage discs. Transducers, in the form of read/write heads attached to the sliders, located on both sides of the storage disc, read and write information on the storage discs when the transducers are accurately positioned over one of the designated tracks on the surface of the storage disc. The transducer is also said to be moved to a target track. As the storage disc spins and the read/write head is accurately positioned above a target track, the read/write head can store data onto a track by writing information representative of data onto the storage disc. Similarly, reading data on a storage disc is accomplished by positioning the read/write head above a target track and reading the stored material on the storage disc. To write on or read from different tracks, the read/write head is moved radially across the tracks to a selected target track. The data is divided or grouped together on the tracks. In some disc drives, the tracks are a multiplicity of concentric circular tracks. Servo feedback information is used to accurately locate the transducer. The actuator assembly is moved to the required position and held very accurately during a read or write operation using the servo information.
One bus interface often used to connect the disc drive into an information-handling system is a SCSI (small computer system interface) bus of one type or another. A plug (typically specified by a SCSI standards committee) is built onto an edge of the disc drive, and is inserted into a socket (also typically specified by the SCSI standards committee) on a SCSI bus. SCSI busses and their respective sockets and plugs can be differential or single-ended (defining the electrical properties), and can be narrow, wide, or ultra-wide (defining the number of connecting wires and pins).
In the manufacture of disc drives, it is desirable to test and xe2x80x9cburn inxe2x80x9d the disc drives as part of the manufacturing process. In some situations, numerous xe2x80x9cbinsxe2x80x9d as many as a thousand or more) are provided in one or more large test stations, each bin having rails to physically hold the disc drive temporarily for the test, and one or more sockets (for example a SCSI bus socket and an electrical power socket) to electrically couple the disc drive to the test system. Manual testing of SCSI bin connectors is tedious, time consuming, and error prone.
In the manufacture of computers or other information-handling systems, SCSI sockets are provided for later connection to SCSI devices such as disc drives. Manual testing of SCSI connectors in manufactured information-handling systems is also tedious, time consuming, and error prone.
There is, therefore, a need for an improved tester and method for testing a connector to bus, for example, for a SCSI connector in a SCSI disc-drive-testing bin or for a SCSI connector in an information-handling system.
A smart tester and method are described for testing a bus connector. In one embodiment, a SCSI bin tester is provided, which tests for various opens and shorts, and for conformance of the voltage supply to its specification.
One aspect of the present invention provides a system for testing a bus connector includes a microprocessor, a first analog multiplexor and an analog demultiplexor both coupled to a first electrical connector, an analog-to-digital converter (ADC) circuit, and a voltage source. The first analog multiplexor is operatively coupled to be controlled by the microprocessor, receiving input from the first electrical connector. The analog-to-digital converter (ADC) circuit is operatively coupled to receive an analog signal from the first analog multiplexor and to provide to the microprocessor a digital signal representative of a voltage on the first electrical connector. The first electrical connector has a plurality of connection pins suitable for connection to the bus connector, and is operatively coupled to provide inputs to the first analog multiplexor. The analog demultiplexor is operatively coupled to be controlled by the microprocessor, and has a plurality of analog output connections operatively coupled to the first electrical connector. The voltage source operatively coupled to provide at least one predetermined voltage as an input to the analog demultiplexor. Such a system allows the bus connector to be tested for shorted faults and opened faults.
Another aspect of the present invention provides a method for testing a bus connector including a plurality of connection pins. The method includes selecting a first test input voltage, automatically controlling a coupling of the first test input voltage to a first one of the connection pins, measuring a voltage of a second one of the connection pins, generating a first digital value representative of the voltage on the second pin that resulted from applying the first voltage to the first pin, automatically comparing the first digital value to a predetermined first expected value, and providing an output indication based on the comparison.
Yet another aspect of the present invention provides an electrical connector having a plurality of connection pins suitable for connection to the bus connector, a voltage source operatively coupled to provide a signal, and automatic means as described herein for serially applying the signal to each one of a first set of the plurality of connection pins and measuring a resulting parameter of each one of a second set of the plurality of connection pins.